Abstract:

Due to the presence of obstacles in the observation site or the unique characteristics of the target object, it is not always possible to lay out survey lines for electrical resistivity tomography in a straight manner. In some cases, even the electrode array cannot be placed directly above the target body. As a result, there are limitations on the application of resistivity tomography method under certain site conditions. This paper focuses on studying 3D electrical resistivity tomography technology for restricted observation sites. The study begins by designing three electrode array observation systems specifically tailored for restricted observation sites: “□” shaped observation system, “U” shaped observation system, and “L” shaped observation system. Subsequently, we investigate the 3D inversion imaging method for determining resistivity using any type of observation system. Finally, we analyze the detection effectiveness of different observation systems through model testing and apply “□” shaped observation system to detect the base structure of an ancient tower in Zhejiang Province. Based on both geoelectric model detection results and the actual site conditions, all three special observation systems for 3D electrical resistivity tomography can effectively capture 3D electrical characteristics below the restricted observation site, thereby providing valuable references for analyzing anomalies within the target area. Among them, the “□” shaped observation system demonstrates the best imaging performance, followed by the “U” shaped observation system, while the “L” shaped observation system shows relatively weak performance. In practical applications, it is essential to consider site conditions and exploration objectives when selecting the electrode array geometry and the number of electrodes, in order to optimize the imaging results.

Key words: restricted observation sites')">

restricted observation sites, unconventional observation system, electrical resistivity tomography